Valve locking devices have been used for some time to prevent unintentional or unauthorized opening and closing of valves. Some known locking devices cooperate with the valve handle to prevent rotation of the handle to the open position when the valve is locked. An advantage of this type of valve locking device is that a visual determination as to whether the valve is in the open position or the closed position can be made even at an appreciable distance from the valve.
The problem with these prior art valves is that they are only capable of locking the valve in the closed position and are unable to lock the valve in the open position. Thus, these prior art valves are unable to prevent the unintentional or unauthorized closing of the valve.
There is therefore a need for a valve locking device which allows the valve to be releasably locked in both the open position and the closed position.